Ceramic ball-and-socket joint

ABSTRACT

A ceramic ball-and-socket joint for a motor vehicle, especially for the chassis of the motor vehicle, is provided, in which the ball-and-socket joint has a ball-and-socket joint housing ( 5 ) provided with a joint opening ( 7 ) and a ball pivot provided with a joint ball ( 1 ) and with a pivot ( 13 ), which said ball pivot is mounted rotatably and pivotably with its joint ball ( 1 ) in a bearing shell ( 2 ) arranged in the ball-and-socket joint housing ( 5 ), wherein the ball pivot protrudes with its pivot ( 13 ) from the ball-and-socket joint housing ( 5 ) through the joint opening ( 7 ). The bearing shell ( 2 ) is divided into at least two separate bearing shell parts ( 3, 4 ), wherein the joint ball ( 1 ) and the bearing shell ( 13 ) are made of a ceramic material.

SPECIFICATION

[0001] The present invention pertains to a ball-and-socket joint for a motor vehicle, especially for the chassis of the motor vehicle, with a ball-and-socket joint housing provided with a joint opening, with a ball pivot, which has a joint ball and a pivot, and which is mounted rotatably and pivotably with its joint ball in a bearing shell arranged in the ball-and-socket joint housing and protrudes with its pivot out of the ball-and-socket joint housing through the joint opening.

[0002] Such a ball-and-socket joint has been known from EP 0 667 464 B1, where the ball pivot is designed as a two-part component. A through opening, through which the pivot of the ball pivot extends, is provided in the joint ball made of metal. The pivot is held by a deformation of a beaded edge of the pivot, which is located within the through opening of the joint ball.

[0003] The ball-and-socket joint is highly sensitive to dirt particles that become incorporated in both the bearing shell and the joint ball once they have entered the interior of the ball-and-socket joint and thus may destroy these on their surfaces. Furthermore, the joint ball is sensitive to rusting, so that shielding against moisture must also be provided besides shielding of the interior of the ball-and-socket joint against dirt.

[0004] This is usually done in conventional ball-and-socket joints by the interior of the ball-and-socket joint being filled with a lubricant and by the opening of the ball-and-socket joint being protected by means of a sealing bellows against the entry of dirt and moisture.

[0005] However, not only do the lubricant and the sealing bellows cause additional costs, but they also lead to an increased manufacturing effort. Furthermore, the ball pivot needs to be longer than would be necessary for purely design reasons without a sealing bellows when a sealing bellows is used in order to achieve a good sealing action.

[0006] Bearing shells known from the state of the art are frequently made from POM, because POM has a low coefficient of friction. However, the use of POM limits the maximum continuous use temperature of the ball-and-socket joint to about 100° C., so that such ball-and-socket joints must not be arranged, e.g., in the immediate vicinity of motor vehicle brakes. POM also has a low maximum possible surface pressure, so that large ball diameters are selected for the joint ball to reduce the surface pressure acting on the bearing shell.

[0007] The basic object of the present invention is to provide a ball-and-socket joint of the type mentioned in the introduction, which can be manufactured at a lower cost at equal mechanical requirements and whose dimensions can be reduced and has a markedly longer service life.

[0008] This object is accomplished according to the present invention by a ball-and-socket joint with the features according to patent claim 1. Preferred variants are claimed in the subclaims.

[0009] The ball-and-socket joint according to the present invention for a motor vehicle, especially for the chassis of the motor vehicle, has a ball-and-socket joint housing provided with a joint opening and a ball pivot, which has a joint ball and a pivot and which is mounted rotatably and pivotably with its joint ball in a bearing shell arranged in the ball-and-socket joint housing, wherein the ball pivot with its pivot protrudes from the ball-and-socket joint housing through the joint opening. The bearing shell is divided into at least two bearing shell parts, wherein the joint ball and the bearing shell are made of a ceramic material.

[0010] The ceramic used is corrosion resistant to water and very hard, so that dirt particles are pulverized between the joint ball and the bearing shell and are rendered ineffective for wear. Thus, the use of a sealing bellows as a protection against contaminants and water can be eliminated in the ball-and-socket joint according to the present invention. However, if the sealing bellows is eliminated, the clamping rings usually used to fasten the sealing bellows can be eliminated as well. The surface of the ceramic used may also have a very low coefficient of friction, so that no lubricant is needed. Besides these possible savings in terms of material, the process steps linked with these materials during the manufacture of the ball-and-socket joint may also be eliminated. Furthermore, the maximum possible surface pressure is considerably higher in the case of a ceramic material than in the case of, e.g., POM, so that smaller ball radii can be selected for the joint ball. The surface of the ceramic material is not subject to wear or is subject to very little wear only, so that the ball-and-socket joint according to the present invention has a markedly longer service life.

[0011] However, the ball-and-socket joint according to the present invention can thus also be made at a lower cost and smaller than a ball-and-socket joint known from the state of the art that is intended for the same use. Furthermore, ceramic is also more insensitive to temperature than POM, which expands the range of use of the ball-and-socket joint according to the present invention.

[0012] The bearing shell may be directly in contact with the ball-and-socket joint housing. However, an intermediate layer made of an elastic material is preferably arranged between the bearing shell and the ball-and-socket joint housing, so that shocks can be transmitted from the bearing shell to the ball-and-socket joint housing or vice versa in a damped manner only. This has a favorable effect on the life of the generally brittle ceramic material and improves the comfort during driving.

[0013] The two separate bearing shell parts may be arranged at spaced locations from one another, and the area between the edges of the two bearing shell parts facing each other is free. However, the intermediate layer preferably extends up into the area between the edges of the two bearing shell parts facing each other, so that these form a uniform bearing body for the joint ball together with the intermediate layer. If the intermediate layer does not extend up to the joint ball, the cavity formed between the intermediate layer and the joint ball may be used to hold dust that is formed, e.g., due to the pulverization of dirt particles.

[0014] On its side facing away from the joint opening, the ball-and-socket joint housing may be closed with a cover, whose edge engages a recess or groove provided in the inner wall of the ball-and-socket joint housing. The intermediate layer now preferably extends up into the recesses and is thus arranged between the cover and the ball-and-socket joint housing.

[0015] The intermediate layer may be manufactured from an elastic material such as rubber. However, the intermediate layer is preferably manufactured from a plastic, because plastics can be regularly designed for a higher temperature resistance and may possess markedly better sliding properties. Furthermore, plastic can often be injection-molded more simply than rubber. The use of injection-moldable materials such as rubber or plastic makes possible the injection molding around the two bearing shell parts to form a common bearing body, which can be held together by the injection-moldable material without clearance. Furthermore, fibers may be embedded in the injection-moldable material in order to increase its load-bearing capacity. The suitable fibers include, e.g., glass, carbon or aramide fibers.

[0016] The intermediate layer is, furthermore, a mounting aid, because the joint ball and the two bearing shells can be sprayed around with plastic or rubber in a mold to form a composite, and this composite will then have a small clearance between the joint ball and the bearing shell and can be mounted in the ball-and-socket joint housing in a simple manner.

[0017] According to a first variant, the two bearing shell parts may be separated from one another with respect to a plane, in which the longitudinal axis of the bearing is located (vertical division). However, a second variant is preferred, according to which a first of the two bearing shell parts is arranged in the area of the ball-and-socket joint housing facing the joint opening with respect to the meridian plane defined by the great circle extending at right angles to the longitudinal axis of the bearing on the joint ball, and the second ball-and-socket joint part is arranged in the area of the ball-and-socket joint housing facing away from the joint opening with respect to the meridian plane. The meridian plane thus forms a division plane between the two bearing shell parts, so that these are located opposite each other with respect to the meridian plane (horizontal division).

[0018] The pivot may likewise be manufactured from a ceramic material. However, the pivot is preferably manufactured from a metallic material and is connected to the joint ball in substance or in a positive-locking manner. It is achieved as a result that the pivot can absorb stronger tensile forces.

[0019] The positive-locking connection between the pivot and the joint ball is preferably achieved by a through opening, through which the pivot extends, being provided in the joint ball. A shoulder which is in contact with the edge of the through opening facing the joint opening, is formed on the pivot, and the pivot is widened up at its end arranged in the joint housing such that the joint ball is fixed to the pivot between the shoulder and the widened end of the pivot in a positive-locking manner.

[0020] The widened end of the pivot may be directly in contact with the joint ball. However, a ring made of metal or an elastic material is preferably inserted between the widened end of the pivot and the joint ball, which makes it possible to distribute the forces applied by the widened end on the joint ball over a larger area. For example, steel may be used as the metal and, e.g., rubber may be used as the elastic material.

[0021] The ceramic material may be made, e.g., on the basis of aluminum oxide, silicon nitride or zirconium oxide. However, the use of so-called “hard metals,” e.g., tungsten carbide or titanium carbide, is possible as well. The list of these materials shall not be considered to be limiting, so that other ceramic materials or mixed ceramic materials, which meet the requirements imposed in the motor vehicle, especially in the chassis of the motor vehicle, may be used as well.

[0022] The surface of the joint ball may be made smooth. However, the surface of the joint ball may also be provided with a profile, so that contaminants can be better removed from the ball-and-socket joint. One possible type of profiling is, e.g., the formation of circular depressions in the surface of the joint ball, similarly to those in a golf ball.

[0023] The present invention will be described on the basis of a preferred embodiment with reference to the drawings. In the drawings,

[0024]FIG. 1 shows a sectional view of an embodiment of the ball-and-socket joint according to the present invention.

[0025] The figure shows an embodiment of the ball-and-socket joint according to the present invention, where a joint ball 1 made of ceramic is mounted rotatably or pivotably in a bearing shell 2 likewise made of ceramic. The bearing shell 2 is divided into two separate bearing shell parts 3 and 4 and is arranged in a ball-and-socket joint housing 5. An intermediate layer 6 made of plastic, which also extends into the area between the edges of the two bearing shell parts 3 and 4 facing each other, is provided between the bearing shell 2 and the ball-and-socket joint housing 5. The ball-and-socket joint housing 5 is a cylindrical body, one front surface of which forms a joint opening 7 and whose other front surface is closed with a cover 8. The cover 8 engages for this an annular groove 9, which is formed in the inner wall of the ball-and-socket joint housing 5 and is formed by flanging the edge 10 of the ball-and-socket joint housing 5 surrounding the cover 8 in the direction of the longitudinal axis 11 of the bearing. The intermediate layer 7 also engages the annular groove 9 and is fixed there between the cover 8 and the ball-and-socket joint housing 5. Even though the cover 8 is closed according to this embodiment, a ring-shaped cover, which leaves the ball-and-socket joint housing open, is also possible.

[0026] A through hole 12, through which a pivot 13 made of metal extends, is provided in the joint ball 1. A ring shoulder 14, which is in contact with the edge of the through hole 12 facing the joint opening 7, is formed on the pivot 13. On the other side of the through hole 12, the pivot is provided with a widening 15, which is pressed via a rubber ring 16 against the edge of the through hole 12 facing away from the joint opening 7. The joint ball 1 is thus fixed at the pivot 13 in a positive-locking manner. To form the widening 15, a cylindrical recess 17, which is surrounded by an edge 18 in a ring-shaped pattern and is concentric to the longitudinal axis 19 of the pivot 13, is provided in the end area of the ball pivot 13 arranged in the ball-and-socket joint housing 5. The edge 18 is flanged radially toward the outside, i.e., in the direction away from the longitudinal axis 19 of the pivot 13, which direction coincides with the bearing longitudinal axis 11 of the ball-and-socket joint in the non-deflected state of the pivot 13 in relation to the ball-and-socket joint housing 5. Furthermore, slots 20 are provided in the edge 18, so that the edge 18 can be flanged more easily.

[0027] List of Reference Numbers

[0028]1 Joint ball

[0029]2 Bearing shell

[0030]3 First bearing shell part

[0031]4 Second bearing shell part

[0032]5 Ball-and-socket joint housing

[0033]6 Intermediate layer

[0034]7 Joint opening

[0035]8 Cover

[0036]9 Annular groove

[0037]10 Edge

[0038]11 Bearing longitudinal axis

[0039]12 Through opening

[0040]13 Pivot

[0041]14 Ring shoulder

[0042]15 Widening of the pivot end arranged in the housing

[0043]16 Rubber ring

[0044]17 Recess

[0045]18 Edge of recess

[0046]19 Longitudinal axis of pivot

[0047]20 Slots

[0048] M Meridian plane 

1. Ball-and-socket joint for a motor vehicle, especially for the chassis of the motor vehicle, with a said ball-and-socket joint housing (5) provided with a said joint opening (7), with a ball pivot, which has a said joint ball (1) and a said pivot (13), and which is mounted rotatably and pivotably with its said joint ball (1) in a said bearing shell (2) arranged in the said ball-and-socket joint housing (5) and protrudes with its said pivot (13) from the said ball-and-socket joint housing (5) through the said joint opening (7), characterized in that the said bearing shell (2) is divided into at least two said separate bearing shell parts (3, 4), and the said joint ball (1) and the said bearing shell (2) are made of a ceramic material.
 2. Ball-and-socket joint in accordance with claim 1, characterized in that a said intermediate layer (6) from an elastic material is arranged between the said bearing shell (2) and the said ball-and-socket joint housing (5).
 3. Ball-and-socket joint in accordance with claim 2, characterized in that the said intermediate layer (6) extends up into the area between the edges of the said two bearing shell parts (3, 4) facing each other.
 4. Ball-and-socket joint in accordance with claim 2 or 3, characterized in that the said ball-and-socket joint housing (5) is closed with a said cover (8), whose edge engages a said recess (9) provided in the inner wall of the said ball-and-socket joint housing (5), and the said intermediate layer (6) extends up into the said recess (9) and is arranged between the said cover (8) and the said ball-and-socket joint housing (5).
 5. Ball-and-socket joint in accordance with claims 2 through 4, characterized in that the said intermediate layer (6) is made of plastic.
 6. Ball-and-socket joint in accordance with one of the claims 1 through 5, characterized in that the said two bearing shell parts (3, 4) are separated from one another with respect to a plane in which the longitudinal axis of the bearing is located.
 7. Ball-and-socket joint in accordance with one of the claims 1 through 5, characterized in that a first of the said two bearing shell parts (3) is arranged in the area of the said ball-and-socket joint housing (5) facing the said joint opening (7) with respect to the said meridian plane (M) defined by the great circle extending at right angles to the said longitudinal axis (11) of the bearing on the joint ball, and the said second bearing shell part (4) is arranged in the area of the said ball-and-socket joint housing (5) facing away from the said joint opening (7) with respect to the said meridian plane (M).
 8. Ball-and-socket joint in accordance with one of the claims 1 through 7, characterized in that the said pivot (13) is made of a metallic material and is connected to the said joint ball (1) in a positive-locking manner.
 9. Ball-and-socket joint in accordance with claim 8, characterized in that a said through hole (12), through which the said pivot (13) extends, is provided in the said joint ball (1); a said shoulder (14), which is in contact with the edge of the said through hole (12) facing the said joint opening (7), is formed on the said pivot (13); and the said pivot (13) is widened at its end arranged in the said ball-and-socket joint housing (5) such that the said joint ball (1) is fixed to the said pivot between the said shoulder (14) and the said widened end (15) of the said pivot (13).
 10. Ball-and-socket joint in accordance with claim 9, characterized in that a said ring (16) made of an elastic material is inserted between the said widened end (15) of the pivot and the said joint ball (1).
 11. Ball-and-socket joint in accordance with one of the claims 1 through 10, characterized in that the ceramic material is made of aluminum oxide, silicon nitride, zirconium oxide, tungsten carbide or titanium carbide. 